SOLUTION: You have 20% NaCl stock solution. You need to prepare 500 ml of a 0.5% NaCl solution? How many ml stock solution do you need to make this preparation? How much water will you add t

Question 811385: You have 20% NaCl stock solution. You need to prepare 500 ml of a 0.5% NaCl solution? How many ml stock solution do you need to make this preparation? How much water will you add to the final product?
Answer by Alan3354(69443) (Show Source): You can put this solution on YOUR website!
You have 20% NaCl stock solution. You need to prepare 500 ml of a 0.5% NaCl solution? How many ml stock solution do you need to make this preparation? How much water will you add to the final product?
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N = amount of 20%
W = amount of water
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N + W = 500 (total solution)
20*N + 0*W= 500*0.5 (total salt)
20N = 250
N = 12.5 ml of 20%
487.5 ml of Water

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